Generally, existing commercially available prostheses, such as active ankle prostheses, are only able to reconfigure joint angle in response to very limited external factors. For example, available microprocessor-controlled ankle prostheses typically are only able to reconfigure ankle joint angle during a swing phase, requiring several strides to converge to a terrain-appropriate ankle position at first ground contact. Further, such ankle prostheses generally do not provide sufficient stance phase power for normal gait, and therefore cannot adapt biomimetically to changes in terrain slope and walking speed. Known control schemes for microprocessor-controlled ankle-foot prostheses rely upon fixed ankle state relationships deemed appropriate for walking at target speeds and across known terrains. Although somewhat effective at their intended steady-state gait speed and terrain, such controllers generally do not allow for adaptation to environmental disturbances such as speed transients and rapid intra-step terrain variations.
Therefore, a need exists for a controller of a robotic limb, such as a robotic leg or ankle, and a method for controlling a robotic limb, that overcomes or minimizes the above-referenced problems.